.net - 使用 If 语句停止加载下一个表单

Question

我的年龄检查不起作用，因此您可以输入您想要的任何年龄，并且它不会显示错误并且不会显示消息框。它允许您输入任何信息并仍然继续。有任何想法吗？

Dim errorcount as Integer = 0

Private Sub btnContinue_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnContinue.Click
    strName = txtName.Text
    strAddress = rtfAddress.Text
    strCity = txtCity.Text
    strEmail = txtEmail.Text
    strHomePhone = mtxtHomePhone.Text
    strMobilePhone = mtxtMobilePhone.Text
    If txtName.Text = "" Then
        MessageBox.Show("You must enter full name", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        errorcount += 1
        Exit Sub
    ElseIf IsNumeric(txtName.Text) Then
        MessageBox.Show("Please enter a valid name", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        errorcount += 1
        Exit Sub
    End If
    If txtAge.Text = "" Then
        MessageBox.Show("You must enter your age", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        errorcount += 1
        Exit Sub
    End If
    'Declaring age check
    Dim AgeCheck As Boolean = False
    If IsNumeric(txtAge.Text) = True Then
        AgeCheck = True
        'strAge = Integer.Parse(txtAge.Text)
    ElseIf strAge < 18 Then
        MessageBox.Show("You must be over 18 years old", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
    ElseIf strAge > 125 Then
        MessageBox.Show("Don't be stupid. You're not that old.", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
    ElseIf AgeCheck = False Then
        MessageBox.Show("You must enter a valid age", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        Exit Sub
    End If
    If Not IsNumeric(txtAge.Text) Then
        MessageBox.Show("Please enter a vadid age", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        errorcount += 1
    End If
    If IsNumeric(rtfAddress.Text) Or rtfAddress.Text = "" Then
        MessageBox.Show("Please enter your address", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        errorcount += 1
        Exit Sub
    End If
    If IsNumeric(txtCity.Text) Or txtCity.Text = "" Then
        MessageBox.Show("Please enter your town/city", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        errorcount += 1
        Exit Sub
    End If
    'if no index hasd been selected
    If cmbCounty.SelectedItem = "" Then
        MessageBox.Show("Please select a county", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        errorcount += 1
        Exit Sub
    End If
    If Not mtxtHomePhone.MaskCompleted Then
        MessageBox.Show("Please enter a valid home phone number", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        errorcount += 1
        Exit Sub
    End If
    If Not mtxtMobilePhone.MaskCompleted Then
        MessageBox.Show("Please enter a valid mobile phone number", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        errorcount += 1
        Exit Sub
    End If
    If txtEmail.Text = "" Then
        MessageBox.Show("You must enter a valid email address", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        errorcount += 1
    ElseIf Not txtEmail.Text.Contains("@") Then
        MessageBox.Show("Not a valid email address", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        errorcount += 1
        Exit Sub
    End If
    If errorcount >= 5 Then
        MessageBox.Show("Too many errors. Shutting down", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Warning)
        Me.Dispose()
        Exit Sub
        'End
        'Exit Sub
    End If
    Me.Hide()
    frmCreditCardInfo.Show()
End Sub
End Class

Answer 1

你的 if 语句 -If IsNumeric(txtAge.Text) = True Then

如果这等于 true，则不会触发 elseif 语句，您只需设置 AgeCheck = True 即可。您将需要稍微修改逻辑

Answer 2

1. 您需要处理何时IsNumeric(txtAge.Text)为假。
2. 遇到错误时需要退出子

试试这个块

If IsNumeric(txtAge.Text) = True Then
    strAge = Integer.Parse(txtAge.Text)
    If strAge < 18 Then
        MessageBox.Show("You must be over 18 years old", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        Exit Sub
    ElseIf strAge > 125 Then
        MessageBox.Show("Don't be stupid. You're not that old.", "Error", MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
        Exit Sub
    End If
Else
    MessageBox.Show("You must enter a valid age", "Error", MessageBoxButtons.OK, _
                    MessageBoxIcon.Error)
    Exit Sub
End If